As an example, JP07-322410A (hereinafter, referred to as reference 1) discloses a vehicle structure including an electric generator for regenerating electricity. According to the reference 1, the electric generator (serving as an auxiliary braking device and an auxiliary driving device) is provided between an internal combustion engine and a transmission (automated transmission). Further, in a condition where torque is transmitted to the electric generator from a drive shaft via the transmission when a braking operation is performed, the electric generator regenerates electricity.
According to the reference 1, in a condition where the braking operation (operation for releasing an accelerator) is performed when the vehicle is driven under an operational state (ON-state) of the accelerator, a motor is used as the electric generator (the auxiliary braking device). The torque is transmitted to the electric generator via the transmission. Therefore, in a speed-changing period in which a clutch is partially engaged or released until speed changing is completed, torque transmission from the drive shaft to the electric generator may be difficult. Further, the amount of the torque regenerated by the electric generator varies as often as the speed changing is performed in association with the amount of battery charge. Accordingly, the control of the speed changing may be difficult. Therefore, the electricity generation is difficult in the speed-changing period.
FIG. 5 illustrates a speed shift stage selecting map (speed shifting map), which is provided at a control apparatus of the transmission and is employed for determining whether or not the speed shift is required on the basis of an accelerator opening degree (a throttle opening degree) and vehicle speed. For example, when the accelerator releasing operation is performed in a condition where the vehicle is driven at a third speed stage with a constant accelerator opening degree (a constant throttle opening degree) as indicated with a point “a” in FIG. 5, the accelerator opening degree is reduced to across an up-shifting operation control line (a continuous line) 3-4. Consequently, the control apparatus for the transmission determines to conduct an up-shifting operation. In a condition where an operator (driver of the vehicle) continues to drive the vehicle even while the accelerator releasing operation is performed, the control apparatus for the transmission may maintain the speed stage (a fourth speed stage) established by performing the up-shifting operation (as indicated with a point “b1”). However, in a condition where the accelerator is largely returned (released) and the throttle opening degree is thereby largely reduced (as indicated with a point “b2”), for example by an intention of the operator to brake the vehicle, at least two consecutive speed changes (one is from the third speed to fourth speed, and the other is from the fourth speed to third speed) are performed. More specifically, in such a condition, after the throttle opening degree is reduced across the up-shifting operation control line 3-4, the up-shifting operation to change the vehicle speed from the third speed to the fourth speed is performed, while the vehicle speed is reduced across a downshift operation control line (a dotted line) 4-3 (as indicated with a point “c”), thereby reducing the vehicle speed from the fourth speed to the third speed. Thus, because of the plural amounts of the speed changing, the electricity is not regenerated efficiently.
A need thus exists for a control apparatus for an automated transmission which is not susceptible to the drawback mentioned above.